ZyXEL Communications ZyXEL ZyWALL IDP 10 - Manual (Page 41)

ZyWALL IDP 10 User’s Guide
Remote Management 5-5
Figure 5-4 SSH Communication Example
5.4.1 How SSH works
The following table summarizes how a secure connection is established between two remote hosts.
1. Host Identification
The SSH client sends a connection request to
the SSH server. The server identifies itself with a
host key. The client encrypts a randomly
generated session key with the host key and
server key and sends the result back to the
server.
The client automatically saves any new server
public keys. In subsequent connections, the
server public key is checked against the saved
version on the client computer.
2. Encryption Method
Once the identification is verified, both the client
and server must agree on the type of encryption
method to use.
Figure 5-5 How SSH Works
3. Authentication and Data Transmission
After the identification is verified and data
encryption activated, a secure tunnel is
established between the client and the server.
The client then sends its authentication
information (user name and password) to the
server to log in to the server.
5.4.2 SSH Implementation on the ZyWALL
Your ZyWALL supports SSH version 1.5 using RSA authentication and three encryption methods
(DES, 3DES and Blowfish). The SSH server is implemented on the ZyWALL for remote management
and file transfer on port 22. Only one SSH connection is allowed at a time.
5.4.3 Requirements for Using SSH
You must install an SSH client program on a client computer (Windows or Linux operating system)
that is used to connect to the ZyWALL over SSH.
5.5 SSH (Secure Shell) Configuration
To change your ZyWALL’s Secure Shell settings, click REMOTE MGNT, then the SSH tab.